Expansion of Sum_{k>=0} (x * (1 + k*x^3))^k.

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =5a(6) =10a(7) =17a(8) =30a(9) =64a(10) =146a(11) =315a(12) =649a(13) =1386a(14) =3164a(15) =7381a(16) =16931a(17) =38649a(18) =90406a(19) =217474a(20) =527586a(21) =1277452a(22) =3112371a(23) =7705059a(24) =19336789a(25) =48800634a(26) =123617380a(27) =315671212a(28) =814711955a(29) =2119996540